This tutorial covers following topics

• Creating a project with Maven.
• Most common errors and their resolutions that you may encounter during project creation.
• Introduction to some common Maven commands.
• Creating a web project with Maven.
• Creating a WAR file with Maven.
• Creating an Eclipse project with Maven.

If you have not set up Maven environment yet, please read the following tutorial before going any further.

http://geekbridage.wordpress.com/2009/02/10/maven-installation-instructions/

• This tutorial does not cover the introduction, usage, advantages or disadvantages of Maven but simply is a guide for dummies who want to start working in Maven for the first time. You can find a lot of detail on the Internet.
• Also you will find notes on some steps which will notify you for any further studies.
• You will also get familiar with common errors and you will be told the solution.
  
• At the end you will find some useful links from where you can learn more about Maven.

Creating a Project in Maven

• First check if maven is installed properly or not with the following command
  
• In console window type this mvn –version. You will see something similar to this

Maven version: 2.0.9

Java version: 1.5.0

OS name: “windows xp” version: “5.1″ arch: “x86″ Family: “windows”

• First create a directory with any name. In my case it is “Maven Examples” anywhere on your hard disk.
• To create a simple Java project, you simply execute the command as shown.

If you don’t know what is archtype, groupId and artifactId, don’t worry you can find a lot of help on the web. Visit the following link if you are anxious to know about the commands http://maven.apache.org/plugins/index.html

• Open your console and go the recently created directory i.e. Maven example

• Give the following command on console

write the whole command in one line

• Provide the above command and press “Enter”. This may take a lot to time. This command may download a lot of dependencies to the maven repository. So let the maven do its job.

Maven repository is mostly located in your_home_folder/.m2 folder. In my case it is C:\Documents and Settings\ali.hammad\.m2. In Linux platform it may be located in your home folder but may be hidden.

If your machine is behind a proxy, maven will be unable to download the dependencies. In that case you may receive an error similar to this one

Reason: Unable to download the artifact from any repository

org.apache.maven.plugins:maven-resources-plugin:pom:2.2 from the specified remote repositories: central (http://repo1.maven.org/maven2)

Problem Resolution

To remove this error go to your maven home directory, you will find a directory with the name “Conf”. Under “Conf”, you will find a file “settings.xml “. Open the file and uncomment the following portion and provide your proxy IP/Port to make maven work.

optional
true
http
192.168.200.16
8080
127.0.0.1

• After executing the command in step 6, following project hierarchy will be automatically created.

• This is an empty project will do nothing as such. This file is essentially analogous to an IDE project file: it contains all of the information about a project, and is the file that Maven 2 uses to act upon to execute commands. The contents of pom.xml:
• Now lets learn a few maven commands. Execute the lifecycle command mvn test on our pom.xml file.

• cd” to the project folder i.e. maven2example_logic and execute the following command

> Your output may differ from mine, because maven may download some dependencies from the web.

> You may also get an error some errors which are described after the screenshot.

You may encounter this error

[INFO] Scanning for projects...
[INFO] ------------------------------------------------------------------------
[INFO] Building Maven Default Project
[INFO]    task-segment: [test]
[INFO] ------------------------------------------------------------------------
[INFO] ------------------------------------------------------------------------
[ERROR] BUILD ERROR
[INFO] ------------------------------------------------------------------------
[INFO] Cannot execute mojo: resources. It requires a project with an existing po
m.xml, but the build is not using one.
[INFO] ------------------------------------------------------------------------
[INFO] For more information, run Maven with the -e switch
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 1 second
[INFO] Finished at: Mon Feb 09 13:47:11 GMT+05:00 2009
[INFO] Final Memory: 2M/4M
[INFO] ------------------------------------------------------------------------

Problem Resolution:

This means you are not in the right directory. Just “cd” to the inner directory. In my case I created a directory “Maven Examples” and then ran the above command. That command created a maven project “maven2example_logic”. So cd to maven examples then maven2example_logic and run the command again.

• Executing the test command will create a “target” directory along with the “src” directory which will contain classes directory.

Creating a Web Project

• Move one step up in the directory structure. So you must be the main directory created at step #2. In my case its “Maven Examples”

• Issue the following command to create a web project

You may get following error at this point

[INFO] Scanning for projects...
[INFO] Searching repository for plugin with prefix: 'archetype'.
[INFO] ------------------------------------------------------------------------
[INFO] Building maven2example_logic
[INFO]    task-segment: [archetype:create] (aggregator-style)
[INFO] ------------------------------------------------------------------------
[INFO] Setting property: classpath.resource.loader.class => 'org.codehaus.plexus
.velocity.ContextClassLoaderResourceLoader'.
[INFO] Setting property: velocimacro.messages.on => 'false'.
[INFO] Setting property: resource.loader => 'classpath'.
[INFO] Setting property: resource.manager.logwhenfound => 'false'.
[INFO] [archetype:create]
[WARNING] This goal is deprecated. Please use mvn archetype:generate instead
[INFO] Defaulting package to group ID: com.dps.maven2example
[INFO] artifact org.apache.maven.archetypes:maven-archetype-webapp: checking for
updates from central
Downloading: http://repo1.maven.org/maven2/org/apache/maven/archetypes/maven-arc
hetype-webapp/1.0/maven-archetype-webapp-1.0.jar
3K downloaded
[INFO] -------------------------------------------------------------------------
---
[INFO] Using following parameters for creating OldArchetype: maven-archetype-web
app:RELEASE
[INFO] -------------------------------------------------------------------------
---
[INFO] Parameter: groupId, Value: com.dps.maven2example
[INFO] Parameter: packageName, Value: com.dps.maven2example
[INFO] Parameter: basedir, Value: C:\Documents and Settings\ali.hammad\Maven Exa
mples\maven2example_logic
[INFO] Parameter: package, Value: com.dps.maven2example
[INFO] Parameter: version, Value: 1.0-SNAPSHOT
[INFO] Parameter: artifactId, Value: maven2example_webapp
[INFO] ------------------------------------------------------------------------
[ERROR] BUILD ERROR
[INFO] ------------------------------------------------------------------------
[INFO] Error creating from archetype

Embedded error: Unable to add module to the current project as it is not of pack
aging type 'pom'
[INFO] ------------------------------------------------------------------------
[INFO] For more information, run Maven with the -e switch
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 6 seconds
[INFO] Finished at: Mon Feb 09 14:29:04 GMT+05:00 2009
[INFO] Final Memory: 7M/13M
[INFO] ------------------------------------------------------------------------

Problem Resolution:

You are in the wrong directory. Move one step up in the hierarchy. Refer to step #11

• You will see something similar to the following figure

• The above command will setup a web project.

Creating WAR File

• Go to the newly created web project and issue the following command

Your output will be similar to the following

Creating an Eclipse Project with Maven

• In the web project type the following command and your eclipse project will be created.

Further Reading

http://today.java.net/pub/a/today/2007/03/01/building-web-applications-with-maven-2.html, Building Web Applications with Maven 2

http://maven.apache.org/guides/getting-started/index.html, Maven Getting started Guide

http://maven.apache.org/guides/getting-started/maven-in-five-minutes.html, Maven in 5 Minutes